568 



GINSBURG, LLOYD, STOCKMAN AND MCCALLUM 



[CHAP. 22 



ill the sediiiuMits derived from them. In these sediments, however, the differ- 

 ences are more a matter of the relative abnndance of different organisms rather 

 than tlieir presence or absence. 



^ 



-'^, 



e 



^v.u: 



/vo \, 





:^^ K_ 



>v_ 



2;i^C: 



V 



^ WIND 



1— 



Sinking 

 2 5-SEC CHOP 



LAGOON 



^^(I 





THICKENING SURFACE CURRENT 



■^TmTTmmTrTTTmj-yTmmmTrrm^^ 



THICK BOTTOM CURRENT 



• "CORAL" ATOLL 



VERTICAL EXAGGERATION — 42 TIMES 



LENGTH OF SECTION — 21 MILES 

 DEPTH OF SECTION 30 FATHOMS 



SWELL 



Z^J:^^ AOMOEN I 



i^' 



BOKORORYURI l\«' 



■■',^-'.'' -'.':': 





'" EXPLANATION ^~9^I^J/ 



• RUKRUKOJI ^^^^AIRUKIIJI I 



Surfoce-woter motions CHANNEL 



Bottom circulation 

 Tide-controlled currents 





y ^' — ■»--- ■ 



ENYU CHANNEL 



BIKINI ATOLL 

 REDRAWN FROM CHART 

 N0.6032 



Fig. 9. Schematic water circulation, Bikini Atoll. (After von Arx, 1954.) 



C. Bikini Atoll 



The contrast between the physical environment of the coral-algal reefs and 

 the lagoon at Bikini is obvious in Fig. 9 (von Arx, 1954). These differences in 

 environment are faitlifnlly recorded by the skeletal sediments (Fig. 10). 

 Halimeda-Tich lagoonal sediments from other Pacific atolls have been reported 

 by Chapman (1901, p. 163), Cloud (1952, p. 27), and McKee, Chronic and 

 Leopold (1959, pp. 507-509). Emery (1956, p. 1512) called attention to the small 



